As described in U.S. patent application Ser. No. 11/525,929 filed Sep. 25, 2006, now U.S. patent No. 7,963,048, issued Jun. 21, 2011, and incorporated by reference herein, in this field, lumber drying was typically performed in a batch process where a quantity of raw moisture laden lumber is piled in one or more stacks and the stacks were moved into a kiln with an insulated chamber through which heated air was moved to effect removal of moisture from the lumber. As will be evident to those skilled in this technology, this was a labor-intensive and time-consuming process which greatly added to the expense of the finished lumber. One of the improvements of the aforementioned application resides in the use of two generally parallel paths for separate continuous drying lines which are moved in opposite directions through a plurality of chambers which are aligned along the separate paths and in communication with one another to increase the efficiency of the drying process. This is accomplished by continuously moving loads of lumber while conserving the heat that builds up in each load as it is continuously moved along one path in the kiln and transferring some of that heat from a load of dried lumber to an incoming load of green lumber moving from the opposite end of the kiln as they pass one another in the kiln. This results in a great economy in the utilization of the heat energy used in the heating zone which is generally centrally located along the two paths.